A novel protection strategy for DC microgrid considering communication failure

Abstract

DC microgrid has become an important part of supporting “carbon peaking, carbon neutralization” and building a low-carbon energy system. However, the short-circuit current of the DC microgrid rises rapidly and has a great impact, threatening the normal operation of the DC microgrid. As the main protection strategy for removing short-circuit faults, current differential protection can quickly and selectively remove fault lines, but it depends on communication. In addition, a high impedance short circuit may also lead to the failure of the current differential protection strategy. To improve the quick action and sensitivity of DC microgrids protection strategy, a differential protection strategy based on the bus power gradient is proposed, and to further solve the problem of protection failure caused by communication failure or communication data loss, an improved composite strategy for DC microgrids considering communication faults is proposed. In the case of normal communication, the power gradient differential protection detects and removes the short-circuit faults; In the case of communication failure, the power gradient differential protection is blocked and local power gradient protection is started. The problem of protection strategy failure caused by communication failure was solved without adding measuring devices. Meanwhile, the power differential gradient changed more violently than the current or voltage during the failure, which improved the protection sensitivity. Finally, simulation and experiment prove the effectiveness of the proposed strategy.

Keywords

• DC microgrid
• Short-circuit fault
• Power gradient
• Differential protection